1. Field of the invention
This invention relates to a seat height adjusting device and particularly relates to a seat height adjusting device with a seat reclining device.
2. Description of the Related Art
A typical vehicle seat has a seat cushion connected to a seat back. The height of the seat cushion and the incline angle of the seat back may be adjusted. If the seat is fixed to the floor or deck of the vehicle, the lateral position of the seat may also be adjusted.
A seat height adjusting device is disclosed in Japanese Patent Laid Open No 6 (114)-127295. The seat height adjusting device includes a first link mechanism and a second link mechanism both disposed at a connecting portion of the seat cushion and the seat back. The first link mechanism includes an upper rail, a lower arm, a lower gear, and a first link member. The second link mechanism includes an upper rail, the lower arm, a second link member, and a cushion frame. The first link mechanism (which is connected to the seat back) is linked to the second mechanism (which is connected to the seat cushion) to adjust the height of the seat cushion while keeping an inclined angle of the seat back relative to the seat cushion.
The seat height adjusting device includes a lock mechanism for preventing the seat cushion from moving vertically. The lock mechanism includes a pawl and a ratchet. The outer teeth of the ratchet engaged the pawl. When an operator pulls an operating lever, the pawl disengages from the ratchet to allow the seat cushion to move vertically.
The known seat height adjusting device must be stiff to prevent the pawl from disengaging from the ratchet if the seat height adjusting device twists during a collision. Therefore, the seat height adjusting device must be enlarged which increases the cost.